1. Field of the Invention
The present invention relates to an endoscope insertion assisting device having a rotary body formed in a toroid or belt shape that rotates to assist in insertion of an insertion part of an endoscope.
2. Description of the Related Art
In endoscopic examination, for example, insertion of an endoscope to the large intestine is very difficult because the large intestine has meandering structure in the body, an unfixed portion is present, or the like. For this reason, much experience is required for acquisition of the skill for insertion of the endoscope into the large intestine, and considerable pain will be inflicted on a subject when insertion skill is inexperienced.
The parts in the large intestine that are said to be particularly difficult to insert the endoscope into are the so-called sigmoid colon and the transverse colon. The reason is that, unlike other parts, the sigmoid colon and the transverse colon are not fixed within the body cavity, and thus, undergo arbitrary shape changes within a range of their own lengths or deform within the body cavity according to the contact force during insertion of the endoscope. For this reason, many techniques have been proposed that make it possible to make the sigmoid colon or the transverse colon straight so as to reduce contact of the endoscope with an intestinal tract during the insertion of the endoscope.
Additionally, an apparatus has also been proposed that self-propels an endoscope in an insertion direction within an intestinal tract so that insertion can be easily performed even if the insertion skill is inexperienced. For example, Japanese Patent Translation Publication No. 2009-513250 discloses an endoscope insertion assisting device having a rotary body formed in a toroidal shape (hollow cylindrical) that rotates to acquire a propulsive force in an insertion direction according to a frictional force generated between the outer surface of the rotary body and the intestinal wall.
In the insertion assisting device disclosed in the above Patent Document, the rotary body is pinched by driving gears arranged so as to have contact with the outer surface of the rotary body and driven rollers arranged so as to face the driving gears with the rotary body therebetween. The rotary body is rotated in accordance with the rotation of the driving gears.
Additionally, the insertion assisting device disclosed in the above Patent Document has two supports, a first support and a second support that are formed in a tubular shape. The first support is provided in a space inside the rotary body, thereby rotatably supporting the rotary body in a direction along the central axis thereof. Additionally, the first support rotatably supports the driven rollers in a state where the first support comes into contact with the inner surface of the rotary body that rotates inside the first support.
The second support is formed in a smaller diameter than the first support, and is held in a state where the second support is inserted through the first support. The second support rotatably supports the driving gears so that the driving gears come into contact with the outer surface of the rotary body that rotates inside of the first support, and holds a transmission mechanism that transmits a driving force to the driving gears. The rotary body is pinched between the driven rollers and the driving gears. Thereby, a driving force is transmitted to the rotary body supported by the respective supports via the transmission mechanism and the driving gears, and the rotary body rotates according to the rotation of the driving gears.
In the insertion assisting device disclosed in Japanese Translation Patent Publication No. 2009-513250, the second support is formed so as to be longer than the first support, and both ends of the second support protrude beyond both ends of the first support. If the ends of the second support protrude beyond the first support in this way, a clearance is formed between the rotary body and the second support at an end portion of the first support where the rotary body is turned.
For this reason, when the rotary body that rotates outside the first support is turned at the end of the first support, and enters between the first support and the second support, the inner wall of a body cavity brought into close contact with the rotary body due to mucus or the like and the inner wall of the body cavity collected on the rear side in a moving direction by the rotation of rotary body may be drawn-in between the respective supports. Such drawing-in of the inner wall of the body cavity will inflict pain on a subject or will cause a decline in propulsive force.